OVA (open virtual appliance) template file is a single archive file in TAR file format that contains files for portability and deployment of virtualization appliances. An OVA template file may include an OVF (open virtual format) descriptor file, optional manifest and certificate files, optional disk images (such as VMware vmdk files), optional resource files (such as ISO's) and other supporting files, such as a message bundle file.
In order to deploy a virtual machine (VM) from an OVA template file, the files of the OVA template file, such as OVF descriptor, vmdk, manifest, certificate, and message bundle files, must be retrieved from the OVA template file at different stages of a deployment process, so that the OVA template file can be validated and any needed file is transferred to the destination host computer on which the VM is to be deployed. Thus, if the OVA template file is located at a remote storage location, the entire OVA template file may first have to be downloaded and the files in the OVA template extracted before the extracted files can be used for deployment. Since the OVA template file is typically a large file, this approach would require significant storage to temporary store the OVA template file.